Greek Symbols

Sigma Symbol

Σ σ

The sigma symbol (Σ / σ) is a letter of the Greek alphabet. This page covers its meaning across mathematics, science, and engineering, its Unicode code point, TeX command, and Windows Alt codes — and you can copy and paste the sigma symbol with one click.

Uppercase Sigma Symbol (Σ)

Σ
SymbolFormatData
ΣUnicodeU+03A3
ΣHTMLΣ
ΣCSS\03a3
ΣJavaScript\u03A3
Σ\SigmaTeX\Sigma
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Greek Capital Letter Sigma (Σ)ImageDownload ↓

Also known as: sigma, summation symbol, sum symbol, sigma notation, summation sign, big sigma, uppercase sigma, sum operator, greek sigma, series symbol.

Σ is the capital form of the Greek letter sigma. Its primary role in mathematics is as the summation operator, written with an index below and an upper limit above to denote the sum of a sequence of terms. It also denotes a covariance matrix in statistics and an alphabet in formal language theory.

∑i=1ni=n(n+1)2\sum_{i=1}^{n} i = \frac{n(n+1)}{2}

Lowercase Sigma Symbol (σ)

σ
SymbolFormatData
σUnicodeU+03C3
σHTMLσ
σCSS\03c3
σJavaScript\u03C3
σ\sigmaTeX\sigma
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Greek Small Letter Sigma (σ)ImageDownload ↓

Also known as: lowercase sigma, greek sigma, sigma symbol, standard deviation symbol, stdev, conductivity symbol, sigma variable.

Sigma (σ) is the eighteenth letter of the Greek alphabet, written σ in lowercase with the word-final variant ς. In statistics σ denotes the standard deviation of a population, and in physics it is used for quantities such as cross-section, conductivity, and surface tension. It also serves as a generic label for permutations in algebra and for dummy variables in analysis.

σ=1N∑i=1N(xi−μ)2\sigma = \sqrt{\frac{1}{N}\sum_{i=1}^{N}(x_i - \mu)^2}

Sigma Symbol Alt Codes

On Windows, hold Alt and type the code on the numeric keypad, then release Alt. Num Lock must be on.

Alt CodeCaseSymbol
Alt228UppercaseΣ
Alt229Lowercaseσ

Codes without a leading zero are legacy OEM codes; they depend on a US English Windows code page.

Customize & Download

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σ
Sigma Symbol — Σ Greek Capital Letter Sigma, σ Greek Small Letter Sigma